Electronic smoking article

ABSTRACT

An electronic smoking article includes a first capillary aerosol generator and a second capillary aerosol generator. The first capillary aerosol generator produces an aerosol having a first particle size distribution and the second capillary aerosol generator produces an aerosol having a second particle size distribution.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to U.S.provisional Application No. 61/798,010, filed on Mar. 15, 2013, theentire content of which is incorporated herein by reference thereto.

WORKING ENVIRONMENT

Many of the embodiments disclosed herein include electronic smokingarticles which include heated capillary aerosol generators. The heatedcapillary volatilizes a liquid such as by way of the teachings set forthin U.S. Pat. No. 5,743,251, which is incorporated herein in its entiretyby reference thereto.

SUMMARY OF SELECTED FEATURES

An electronic smoking article comprising a first capillary aerosolgenerator which produces a first aerosol of a first liquid materialincluding flavor material and a second capillary aerosol generator whichproduces a second aerosol of a second liquid material, the second liquidmaterial including nicotine. The first aerosol has a first particle sizedistribution and the second aerosol has a second particle sizedistribution.

A method of forming an aerosol containing two particle sizedistributions comprises supplying a first liquid containing flavormaterial to a first capillary tube, supplying a second liquid containingnicotine to a second capillary tube, simultaneously heating the firstcapillary tube and the second capillary tube to a temperature sufficientto volatilize the first liquid and the second liquid to form a firstvapor and a second vapor, mixing the first vapor with air to produce afirst aerosol, mixing the second vapor with air to produce a secondaerosol, and combining the first and second aerosols in a mixingchamber. The heating of the first capillary tube and the heating of thesecond capillary tube can occur within a puff cycle at different timeswithin the puff cycle. Moreover, the heating of the first capillary tubeand the heating of the second capillary tube occur within a puff cycleand achieve different temperatures within the puff cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an electronic smoking article.

FIG. 2 is a cross-sectional view of the electronic smoking article ofFIG. 1.

FIG. 3 is an illustration of a capillary tube having a constrictionadjacent an outlet of the capillary tube.

FIG. 4 is a cross-sectional view of a second embodiment of an electronicsmoking article including two capillary aerosol generators.

DETAILED DESCRIPTION

An electronic smoking article, such as an electronic cigarette or anelectronic cigar, is described herein which produces an aerosol havingtwo different particle size distributions. A first particle sizedistribution is formed using a first capillary aerosol generator havinga first liquid supply reservoir that contains liquid material. A secondparticle size distribution is formed using a second capillary aerosolgenerator having a second liquid supply reservoir that contains liquidmaterial. The first liquid material can include flavor material and thesecond liquid material can include nicotine. The first liquid supplyreservoir and the second liquid supply reservoir can contain liquidshaving different viscosities.

Advantageously, by providing an aerosol with two different particle sizedistributions, the aerosol can be tailored to provide desired flavorand/or therapeutic compositions. For example, the flavor compounds canhave a larger median particle size so as to be deposited in the mouthand throat, while functional compounds, such as nicotine or therapeuticcompounds can be provided in smaller particle sizes so as to deliver theparticles deeper into the lower respiratory tract.

As shown in FIG. 1, an electronic smoking article 60 comprises areplaceable cartridge (or first section) 70 and a reusable fixture (orsecond section) 72, which are coupled together at a threaded joint 74 orby other convenience such as a snug-fit, snap-fit, detent, clamp and/orclasp.

The first section 70 can house a mouth-end insert 20, two capillarytubes 18 a, 18 b, two heaters 19 a, 19 b to heat at least a portion ofeach capillary tube 18 a, 18 b (which may comprise a heatable portion 19a, 19 b of the capillary tube 18 a, 18 b itself) and two liquid supplyreservoirs 14 a, 14 b. The second section 72 can house a power supply12, control circuitry 11 and a puff sensor 16. A threaded portion of thesection 72 can be connected to a battery charger when not connected tothe first section 70 for use so as to charge the battery.

Preferably, the first section 70 and the second section 72 include anouter cylindrical housing 22 extending in a longitudinal direction alongthe length of the electronic smoking article 60. Preferably, the outertube 6 is formed of a metal and is part of the electrical circuit. Inother embodiments, the outer tube 6 can formed of any suitable materialor combination of materials. Examples of suitable materials includemetals, alloys, plastics or composite materials containing one or moreof those materials, or thermoplastics that are suitable for food orpharmaceutical applications, for example polypropylene,polyetheretherketone (PEEK), ceramic, and polyethylene. Preferably, thematerial is light and non-brittle.

In one embodiment, the first section 70 is disposable and the secondsection 72 is reusable. In another embodiment, both the first section 70and the second section 72 are disposable. The sections 70, 72 can beattached by a threaded connection.

In the preferred embodiment, each liquid supply reservoir 14 a, 14 b isa tubular, elongate body that holds a predetermined quantity of liquidmaterial. Preferably, each liquid supply reservoir 14 a, 14 b ispressurized such that the liquid material therein is under constantpressure. As shown in FIG. 2, each liquid supply reservoir 14 a, 14 bcan include a pressurization arrangement 50 a, 50 b, such as an internalor external spring and plate arrangement which constantly appliespressure to each liquid supply reservoir 14 a, 14 b. For example, eachliquid supply reservoir 14 a, 14 b can be compressible and positionedbetween two plates that are connected by springs. Alternatively, eachliquid supply reservoir 14 a, 14 b could be compressible and positionedbetween the outer housing and a plate and the plate and outer housingcould be connected by a spring so that the plate applies pressure toeach liquid supply reservoir 14 a, 14 b.

Preferably, each liquid supply reservoir 14 a, 14 b has an outlet 16 a,16 b which is in fluid communication with a capillary tube 18 a, 18 b. Avalve 40 a, 40 b connects each outlet 16 a, 16 b to the respectivecapillary tube 18 a, 18 b so as to prevent flow of liquid material whenthe electronic smoking article 60 is not in use. When each valve 40 a,40 b is opened, each liquid supply reservoir 14 a, 14 b can deliver avolume of liquid material to one of the capillary tubes 18 a, 18 b.During delivery of liquid to the capillary tubes 18 a, 18 b, the powersupply 12 is activated and each capillary tube 18 a, 18 b is heated toform a heated section wherein the liquid material is volatilized. Upondischarge from the heated capillary tubes 18 a, 18 b, two streams ofvolatilized material mix with air that enters the electronic smokingarticle 60 via air inlets 44, and form two aerosols which are combinedin a mixing chamber 46.

Preferably, each liquid supply reservoir 14 a, 14 b extendslongitudinally within the outer cylindrical housing 22 of the firstsection 70. Moreover, each liquid supply reservoir 14 a, 14 b cancomprise a different liquid material which is volatilized when heatedand forms an aerosol. Each aerosol can have the same or differentparticle size distributions. For example, the liquid supply reservoir 14a can include flavor material, while the liquid supply reservoir 14 bcan include a tobacco derived ingredient, such as nicotine.

In the preferred embodiment, each capillary tube 18 a, 18 b includes aninlet end 62 a, 62 b in fluid communication with the outlet 16 a, 16 bof the liquid supply reservoir 14 a, 14 b, and an outlet end 63 a, 63 boperable to expel volatilized liquid material from each capillary tube18 a, 18 b. In some embodiments, one or both capillary tube 18 a, 18 bcan include a constriction 101 a (shown in FIG. 3) at an outlet end 63a, 63 b of the capillary tube 18 a, 18 b. While not wishing to be boundby theory, it is believed that the addition of a constriction at theoutlet of the capillary tube, which reduces the cross-sectional area ofthe outlet end, can create sufficiently high shear forces to break upcoarse droplets, which can increase the conversion of the liquidmaterial to small particles.

Preferably, each capillary tube 18 a, 18 b has a different internaldiameter so as to aid in promoting formation of an aerosol having aparticular particle size distribution. For example, each of thecapillary tubes 18 a, 18 b can have an internal diameter of 0.01 to 10mm, preferably 0.05 to 1 mm, and more preferably 0.05 to 0.4 mm. Forexample, the capillary tube 18 a can have an internal diameter of about0.05 mm and the capillary tube 18 b can have an internal diameter ofabout 0.4 mm. Capillary tubes of smaller diameter provide more efficientheat transfer to the fluid because, with the shorter the distance to thecenter of the fluid, less energy and time is required to vaporize theliquid.

Also preferably, each capillary tube 18 a, 18 b may have a length ofabout 5 mm to about 72 mm, more preferably about 10 mm to about 60 mm orabout 20 mm to about 50 mm. For example, each capillary tube 18 a, 18 bcan be about 50 mm in length and arranged such that a downstream, about40 mm long portion of the capillary tube 18 a, 18 b forms a coiledheated section and an upstream, about 10 mm long portion of thecapillary tube 18 a, 18 b remains relatively unheated when the heater 19a, 19 b is activated.

In one embodiment, each capillary tube 18 a, 18 b is substantiallystraight. In other embodiments, one or both capillary tubes 18 a, 18 bare coiled and/or include one or more bends therein to conserve space.

In the preferred embodiment, each capillary tube 18 a, 18 b is formed ofa conductive material, and thus acts as its own heater 19 a, 19 b bypassing current through the tube. The capillary tubes 18 a, 18 b may beany electrically conductive material capable of being resistivelyheated, while retaining the necessary structural integrity at theoperating temperatures experienced by the capillary tubes 18 a, 18 b,and which is non-reactive with the liquid material. Suitable materialsfor forming the capillary tubes 18 a, 18 b are selected from the groupconsisting of stainless steel, copper, copper alloys, porous ceramicmaterials coated with film resistive material, Inconel® available fromSpecial Metals Corporation, which is a nickel-chromium alloy, nichrome,which is also a nickel-chromium alloy, and combinations thereof.

In one embodiment, each capillary tube 18 a, 18 b is a stainless steelcapillary tube 18 a, 18 b, a portion of which serves as a heater 19 a,19 b. The heater 19 a, 19 b is established between electrical leads 26a, 26 b and an electrical connection 110 adjacent the outlet ends 63 a,63 b of the capillary tubes 18 a, 18 b. Thus, a direct or alternatingcurrent passes along a length of the capillary tube 18 a, 18 b to formthe heater 19 a, 19 b. The first and second capillary tubes can beelectrically connected in series such that the first and secondcapillary tubes 18 a, 18 b are heated by passing electrical current fromthe power source along the first capillary tube, through the electricalconnection interconnecting the first and second capillary tubes, andalohg the second capillary tube, such that the electrical current iseffective to heat the capillary tubes to a temperature sufficient tovolatilize liquid material contained therein as in U.S. Pat. No.6,715,487 which is incorporated herein in its entirety by referencethereto. In an alternative embodiment, the capillary tubes 18 a, 18 bcan be connected in parallel.

Thus, the stainless steel capillary tube 18 a, 18 b is heated byresistance heating. The stainless steel capillary tube 18 a, 18 b ispreferably circular in cross section. The capillary tube 18 a, 18 b maybe of tubing suitable for use as a hypodermic needle of various gauges.For example, the capillary tube 18 a, 18 b may comprise a 32 gaugeneedle has an internal diameter of 0.11 mm and a 26 gauge needle has aninternal diameter of 0.26 mm.

In another embodiment, the capillary tube 18 a, 18 b may be anon-metallic tube such as, for example, a glass tube. In such anembodiment, the heater 19 a, 19 b is formed of a conductive materialcapable of being resistively heated, such as, for example, stainlesssteel, nichrome or platinum wire, arranged along the glass tube. Whenthe heater arranged along the glass tube is heated, liquid material inthe capillary tube 18 a, 18 b is heated to a temperature sufficient toat least partially volatilize liquid material in the capillary tube 18a, 18 b. In other embodiments, one capillary tube 18 a can be stainlesssteel and one capillary tube 18 b can be a glass tube.

Preferably, as shown in FIG. 2, that electrical leads 26 a, 26 b and theelectrical connection 110 are bonded to the metallic capillary tubes 18a, 18 b. In the preferred embodiment, the electrical leads 26 a, 26 bare brazed to the capillary tubes 18 a, 18 b. Preferably, one electricallead 26 a is brazed to a first, upstream portion of the first capillarytube 18 a and a second electrical lead 26 b is brazed to an upstreamportion of the second capillary tube 18 b as shown in FIG. 2.

In use, once each capillary tube 18 a, 18 b is heated, the liquidmaterial contained within a heated portion of each capillary tube 18 a,18 b is volatilized and ejected out of the outlet 63 a, 63 b where itexpands and mixes with air from one or more air inlets 44 and forms anaerosol in a mixing chamber 46.

Preferably, the electronic smoking article 60 includes at least one airinlet 44 operable to deliver air to the mixing chamber 46. Preferably,the air inlets 44 to the mixing chamber 46 are arranged downstream ofthe capillary tubes 18 a, 18 b so as to minimize drawing air along thecapillary tube and thereby avoid cooling of the capillary tubes 18 a, 18b during heating cycles. In use, the volatilized material expands out ofeach capillary tubes 18 a, 18 b and into the mixing chamber 46 where itcan mix with air to form an aerosol which is then drawn through themouth-end insert 20. In the preferred embodiment, the at least one airinlet 44 includes one or two air inlets. Alternatively, there may bethree, four, five or more air inlets 44. Altering the size and number ofair inlets 44 can also aid in establishing the resistance to draw of theelectronic smoking article 60.

In the preferred embodiment, each liquid supply reservoir 14 a, 14 b mayinclude an electrically operated or a mechanically operated valve 40 a,40 b, shown in FIG. 2. Each valve 40 a, 40 b is operable to maintain theliquid material within the liquid supply, but opens when the electronicsmoking article 60 is activated. Preferably, the electronic smokingarticle is manually activated by pressing a button (pressure switch) 100(shown in FIG. 1), which opens the valves 40 a, 40 b and simultaneouslyactivates the heaters 19 a, 19 b. In other embodiments, the valves 40 a,40 b and the heaters 19 a, 19 b can be puff activated, such that when asmoker draws upon the electronic smoking article 60, the puff sensor 16communicates with the control circuitry 11 to activate the heaters 19 a,19 b and open the valves 40 a, 40 b.

Preferably, if the button 100 is used to manually activate theelectronic smoking article 60, the valve 40 a, 40 b opens when acritical, minimum pressure is reached so as to avoid inadvertentdispensing of liquid material from the liquid supply reservoirs 14 a, 14b or activating the heaters 19 a, 19 b. Preferably, the pressurerequired to press the button 100 is high enough such that accidentalheating is avoided. Such arrangement avoids activation of the heaters 19a, 19 b in the absence of liquid being pumped through the capillarytube.

Advantageously, the use of valves 40 a, 40 b also aids in limiting theamount of liquid that is drawn back from each capillary tube uponrelease of pressure upon the liquid supply reservoir 14 (and/or theswitch 44). Withdrawal of liquid from the capillary tube at conclusionof a puff (or activation) is desirous. The presence of residual liquidin the capillary tube at the initiation of a new puff cycle can lead toundesirable sputtering of liquid from the heated capillary tube at thebeginning of activation. The valves 40 a, 40 b can be configured toallow a desired, limited amount of drawback to occur, such that drawbackof liquid occurs without air being drawn into the liquid supplyreservoirs 14 a, 14 b.

Advantageously, each capillary tube 18 a, 18 b is purged once a smokerhas stopped drawing on the electronic smoking article 60 or has stoppedpushing the button 100 because any liquid remaining in the tube isexpelled (volatilized) during heating.

In the preferred embodiment, the power supply 12 includes a batteryarranged in the electronic smoking article 60. The heaters 19 a, 19 bcan be connected to the battery by the electrical leads 26 a, 26 b. Thepower supply 12 is operable to apply voltage across the heaters 19 a, 19b associated with the capillary tubes 18 a, 18 b and volatilize liquidmaterial contained therein according to a power cycle of either apredetermined time period, such as a 2 to 10 second period, or for solong as pressure is applied to the button (pressure switch) 100. Thecontrol circuitry 11 can be programmable and can include amicroprocessor programmed to carry out functions such as heating thecapillary tubes and/or operating the valves. In other embodiments, thecontrol circuitry 11 can include an application specific integratedcircuit (ASIC).

Preferably, the electrical contacts or connection between the heaters 19a, 19 b and the electrical leads 26 a, 26 b are highly conductive andtemperature resistant while the heatable portions 19 a, 19 b of thecapillary tubes 18 a, 18 b are highly resistive so that heat generationoccurs primarily along the heaters 19 a, 19 b and not at the contacts.

The battery can be a Lithium-ion battery or one of its variants, forexample a Lithium-ion polymer battery. Alternatively, the battery may bea Nickel-metal hydride battery, a Nickel cadmium battery, aLithium-manganese battery, a Lithium-cobalt battery or a fuel cell. Inthat case, preferably, the electronic smoking article 60 is usable by asmoker until the energy in the power supply is depleted. Alternatively,the power supply 12 may be rechargeable and include circuitry allowingthe battery to be chargeable by an external charging device. In thatcase, preferably the circuitry, when charged, provides power for apre-determined number of puffs, after which the circuitry must bere-connected to an external charging device.

Preferably, the electronic smoking article 60 also includes controlcircuitry which can be on a printed circuit board 11. Once the button100 (pressure switch) is pressed, the power supply 12 is activated andsupplies power to the heaters 19 a, 19 b. The control circuitry 11 canalso include a heater activation light 27 operable to glow when theheaters 19 a, 19 b are activated. Preferably, the heater activationlight 27 comprises at least one LED and is at an upstream end 5 (shownin FIG. 1) of the electronic smoking article 60 so that the heateractivation light 27 takes on the appearance of a burning coal during apuff. Moreover, the heater activation light 27 can be arranged to bevisible to the smoker. In addition, the heater activation light 27 canbe utilized for smoking article system diagnostics. The light 27 canalso be configured such that the smoker can activate and/or deactivatethe light 27 when desired, such that the light 27 would not activateduring smoking if desired.

Preferably, when activated, the heaters 19 a, 19 b heat a portion of thecapillary tubes 18 a, 18 b for less than about 10 seconds, morepreferably less than about 7 seconds. Thus, the power cycle (or maximumpuff length) can range in period from about 2 seconds to about 10seconds (e.g., about 3 seconds to about 9 seconds, about 4 seconds toabout 8 seconds or about 5 seconds to about 7 seconds).

In the preferred embodiment, the liquid supply reservoirs 14 a, 14 beach include a liquid material which has a boiling point suitable foruse in the electronic smoking article 60. If the boiling point is toohigh, the heaters 19 a, 19 b will not be able to vaporize liquid in thecapillary tubes 18 a, 18 b. However, if the boiling point is too low,the liquid may vaporize without the heaters 19 a, 19 b being activated.

Preferably, the liquid supply reservoirs 14 a, 14 b each contain adifferent liquid material having different viscosities. The first liquidsupply reservoir 14 a can include at least one flavor material. Thesecond liquid supply reservoir 14 b can include at least one tobaccoderived ingredient, such as nicotine. Preferably, the liquid material inthe second liquid supply reservoir 14 b is more viscous at roomtemperature than the liquid material in the first liquid supplyreservoir 14 a. Moreover, the capillary tube 18 b, associated with thesecond liquid supply reservoir 14 b, preferably has a larger internaldiameter than the capillary tube 18 a associated with the first liquidsupply reservoir 14 a. Accordingly, the first capillary tube 18 aproduces aerosol having particles ranging in size from about 0.4 micronto about 2 microns depending on the flavor material included in theliquid supply reservoir 14 a and the viscosity thereof. The secondcapillary tube 18 b produces an aerosol having particles ranging in sizefrom about 0.5 micron to about 1 micron. Advantageously, the electronicsmoking article can be configured to form a first aerosol having largerparticles for delivery to the mouth and a second aerosol having smallerparticles for delivery to the lower respiratory tract if desired.

The second liquid supply reservoir 14 b can include nicotine. The firstliquid supply reservoir 14 a can include flavor material, a non-tobaccomaterial and/or may be nicotine-free. For example, the liquid materialin the first liquid supply reservoir 14 a may include water, solvents,ethanol, plant extracts and natural or artificial flavors. Preferably,the liquid in each of the first liquid supply reservoir 14 a and thesecond liquid supply reservoir 14 b can include an aerosol former.Examples of suitable aerosol formers are glycerine and propylene glycol.

As shown in FIG. 2 the electronic smoking article 60 further includes amouth-end insert 20 having at least two off-axis, preferably divergingoutlets 21. Preferably, the mouth-end insert 20 is in fluidcommunication with the mixing chamber 46 and includes at least twodiverging outlets 21. (e.g, 3, 4, 5, or preferably 6 to 10 outlets ormore). Preferably, the outlets 21 of the mouth-end insert 20 are locatedat ends of off-axis passages 23 and are angled outwardly in relation tothe longitudinal direction of the electronic smoking article 60 (i.e.,divergently). As used herein, the term “off-axis” denotes at an angle tothe longitudinal direction of the electronic smoking article 60. Alsopreferably, the mouth-end insert (or flow guide) 20 includes fouroutlets uniformly distributed around the mouth-end insert 20 so as tosubstantially uniformly distribute aerosol in a smoker's mouth duringuse. Thus, as the aerosol passes into a smoker's mouth, the aerosolenters the mouth and moves in different directions so as to provide afull mouth feel as compared to electronic smoking articles having anon-axis single orifice which directs the aerosol to a single location ina smoker's mouth.

In addition, the outlets 21 and off-axis passages 23 are arranged suchthat droplets of unaerosolized liquid material carried in the aerosolimpact interior surfaces 25 of the mouth-end insert 20 and/or interiorsurfaces of the off-axis passages 23 such that the droplets are removedor broken apart. In the preferred embodiment, the outlets 21 of themouth-end insert 20 are located at the ends of the off-axis passages 23and are angled at 5 to 60° with respect to the central longitudinal axisof the electronic smoking article 60 so as to more completely distributeaerosol throughout a mouth of a smoker during use and to removedroplets.

Preferably, each outlet 21 has a diameter of about 0.015 inch to about0.090 inch (e.g., about 0.020 inch to about 0.040 inch or about 0.028inch to about 0.038 inch). The size of the outlets 21 and off-axispassages 23 along with the number of outlets 21 can be selected toadjust the resistance to draw (RTD) of the electronic smoking article60, if desired.

Preferably, the mouth-end insert 20 is affixed within the outercylindrical housing 22 of the cartridge 70.

In a preferred embodiment, the electronic smoking article 60 is aboutthe same size as a conventional cigarette. In some embodiments, theelectronic smoking article 60 can be about 80 mm to about 110 mm long,preferably about 80 mm to about 100 mm long and about 7 mm to about 8 mmin diameter. For example, in an embodiment, the electronic smokingarticle is about 84 mm long and has a diameter of about 7.8 mm.

The outer cylindrical housing 22 of the electronic smoking article 60may be formed of any suitable material or combination of materials.Preferably, the outer cylindrical housing 22 is formed of metal.Examples of suitable materials include metals, alloys, plastics orcomposite materials containing one or more of those materials, orthermoplastics that are suitable for food or pharmaceuticalapplications, for example polypropylene, polyetheretherketone (PEEK),ceramic, low density polyethylene (LDPE) and high density polyethylene(HDPE). Preferably, the material is light and non-brittle. The outercylindrical housing 22 can be any suitable color and/or can includegraphics or other indicia printed thereon.

When the word “about” is used in this specification in connection with anumerical value, it is intended that the associated numerical valueinclude a tolerance of ±10% around the stated numerical value. Moreover,when reference is made to percentages in this specification, it isintended that those percentages are based on weight, i.e., weightpercentages.

Moreover, when the words “generally” and “substantially” are used inconnection with geometric shapes, it is intended that precision of thegeometric shape is not required but that latitude for the shape iswithin the scope of the disclosure. When used with geometric terms, thewords “generally” and “substantially” are intended to encompass not onlyfeatures which meet the strict definitions but also features whichfairly approximate the strict definitions.

It will now be apparent that a new, improved, and nonobvious electronicsmoking article has been described in this specification with sufficientparticularity as to be understood by one of ordinary skill in the art.Moreover, it will be apparent to those skilled in the art that numerousmodifications, variations, substitutions, and equivalents exist forfeatures of the electronic smoking article which do not materiallydepart from the spirit and scope of the invention. Accordingly, it isexpressly intended that all such modifications, variations,substitutions, and equivalents which fall within the spirit and scope ofthe invention as defined by the appended claims shall be embraced by theappended claims.

We claim:
 1. An electronic smoking article comprising: a first capillary aerosol generator which produces a first aerosol of a first liquid material including flavor material; and a second capillary aerosol generator which produces a second aerosol of a second liquid material, the second liquid material including nicotine, wherein the first aerosol has a first particle size distribution and the second aerosol has a second particle size distribution.
 2. The electronic smoking article of claim 1, wherein the first capillary aerosol generator comprises: a first capillary tube having a first capillary inlet and a first capillary outlet, the first capillary inlet in communication with the first liquid material; and a first heater operable to heat the first capillary tube to a temperature sufficient to volatilize the first liquid material contained within the first capillary tube.
 3. The electronic smoking article of claim 2, wherein the second capillary aerosol generator comprises: a second capillary tube having a second capillary inlet and a second capillary outlet, the second capillary inlet in communication with the second liquid material; and a second heater operable to heat the second capillary tube to a temperature sufficient to volatilize the second liquid material contained within the second capillary tube.
 4. The electronic smoking article of claim 3, wherein the first liquid material and the second liquid material have different room temperature viscosities.
 5. The electronic smoking article of claim 3, wherein the first liquid material comprises flavor material and the second liquid material comprises nicotine.
 6. The electronic smoking article of claim 3, wherein an internal diameter of the first capillary tube is smaller than an internal diameter of the second capillary tube.
 7. The electronic smoking article of claim 3, further comprising: a power supply operable to apply voltage across the first heater and the second heater; a mixing chamber downstream of the first capillary tube and the second capillary tube; and at least one air inlet operable to deliver air into the mixing chamber during drawing on the electronic smoking article.
 8. The electronic smoking article of claim 6, wherein each of the first capillary tube and the second capillary tube has an internal diameter of about 0.05 to 0.4 mm and a length of about 5 mm to about 72 mm or about 10 mm to 60 mm.
 9. The electronic smoking article of claim 6, wherein each of the first capillary tube and the second capillary tube comprise a stainless steel tube or a non-metallic tube.
 10. The electronic smoking article of claim 7, wherein the power supply includes a battery.
 11. The electronic smoking article of claim 10, wherein the first heater is connected to the battery by two spaced apart electrical leads and wherein the second heater is connected to the battery by two spaced apart electrical leads.
 12. The electronic smoking article of claim 10, wherein the first heater and the second heater are connected in series.
 13. The electronic smoking article of claim 7, further including control circuitry operable to control supply of power from the power supply to the first heater and the second heater.
 14. The electronic smoking article of claim 13, wherein the control circuitry further includes a heater activation light at an upstream end of the electronic smoking article, the heater activation light operable to light up when the first heater and the second heater are activated.
 15. The electronic smoking article of claim 3, further including a first valve between a first pressurized liquid supply and the first capillary inlet.
 16. The electronic smoking article of claim 15, further including a second valve between a second outlet of a second pressurized liquid supply and the second capillary inlet.
 17. The electronic smoking article of claim 16, wherein the first valve and the second valve are electrically operated valves and the electronic smoking article further includes a pressure switch, the pressure switch operable to send a signal to open the first valve and the second valve and to send a signal to the control circuitry to supply power to the first heater and the second heater.
 18. The electronic smoking article of claim 3, further including a puff sensor operable to sense a draw on the electronic smoking article.
 19. The electronic smoking article of claim 7, wherein the electronic smoking article includes a first section and a second section and wherein the first section contains the first capillary aerosol generator and the second capillary aerosol generator and the second section contains the power supply and control circuitry operable to control heating of the first and second heaters.
 20. The electronic smoking article of claim 19, wherein the first section is replaceable and the second section is reusable.
 21. A method of forming an aerosol containing two particle size distributions comprising: supplying a first liquid containing flavor material to a first capillary tube; supplying a second liquid containing nicotine to a second capillary tube; simultaneously heating the first capillary tube and the second capillary tube to a temperature sufficient to volatilize the first liquid and the second liquid to form a first vapor and a second vapor; mixing the first vapor with air to produce a first aerosol; mixing the second vapor with air to produce a second aerosol; and combining the first and second aerosols in a mixing chamber.
 22. The method of claim 21, wherein the first aerosol comprises particles ranging in size from about 0.4 micron to about 2 microns.
 23. The method of claim 21, wherein the second aerosol comprises particles ranging in size from about 0.5 micron to about 1 micron.
 24. The method of claim 21, wherein the heating of the first capillary tube and the heating of the second capillary tube occur within a puff cycle at different times within the puff cycle.
 25. The method of claim 21, wherein the heating of the first capillary tube and the heating of the second capillary tube occur within a puff cycle and achieve different temperatures within the puff cycle. 